Methods: A systematic search of 18 databases and interfaces was conducted to identify peer-reviewed articles that included the following criteria: 1) experimental or quasi-experimental group designs or pilot study; 2) quantitative statistical analyses; 3) sample of school age children and adolescents; 4) the studies targeted on increasing empathy or cognitions of bystanders; 5) English. The methodological rigor of each study was assessed using an adapted 10-item version of Methodological Quality Rating Scale (MQRS) to distinguish between the low and high rigor (using median split), and to identify areas of methodological strengths and weaknesses. An outcome attainment score was created by combining the level of methodological rigor with statistical significance of each outcome measure. The primary outcome of this review was the empathy of the bystander, for the victims and beliefs of bystander related to intentions and/or confidence to intervene. The effectiveness of two intervention types (teacher-led information session vs. experiential) and dosage (0-3 vs. 4-7 vs. 8+ sessions) were compared for each outcome.
Results: Thirteen studies met the inclusion criteria. Six interventions were teacher-led information sessions and 7 studies used experiential methods such as drama, video and board games, and virtual reality. Results of the MQRS indicated that the total scores ranged from 6 to 13, of a possible range of 0-13, with a median score of 8. Nine studies of 13 were of high rigor. Six studies reported a significant effect on increasing empathy, four of which were of high rigor. Three teacher-led information interventions were the most effective on this primary outcome. Two experiential interventions were more effective in changing beliefs of bystanders. Interventions with or greater than 8 sessions indicated stronger evidence for improving both outcomes. Number of intervention session was associated with effectiveness of both outcomes.
Conclusions and Implications: Teacher-led information interventions reported stronger evidence for changing empathy for victims than experiential. Conversely, experiential interventions produced more significant outcomes in improving the cognition of bystanders than teacher-led information. Findings suggest that designing types and dosage may be important factors to consider depending on the outcome desired for bullying prevention programs.